The idea of Unity gain is to say what goes in is what goes out, in terms of Level.

this is what is desired when, like me, you use an external preamp or channel strip and you want the output Level of the external hardware to be accurately transferred for recording or live situations.

i don't want the studiolive's AUX IN to attenuate or amplify the signal, just pass it through.

can anyone confirm the 2" o'clock position = Unity gain ? my studiolive does not have the markings on the AUX INs, only on the preamp gain knobs which i suspect has different line opamps and gain staging then the AUX IN.

For the Aux inputs I suggest you use the output meters as a guide: connect a steady signal (e.g. a sine wave) to a channel line input, set input gain to "U" and the channel fader to unity and set the main fader for an easy to remember output meter reading.Then connect the test signal to an Aux input and adjust the input pot for the same output meter reading. That should then be the unity setting.

Still, the classic SLs weren't very good at level in = level out at unity. At unity they tend to add gain.